Engineering plastics are widely utilized in various fields such as OA (office automation) machineries, information/communications equipment, electricity/electronic equipment, electric appliances, automobile fields and construction fields based on their excellent mechanical strength, heat resistance, electrical characteristics, dimensional stability and so on. However, when, for example, a polycarbonate resin is used, it has problems that melt flowability is inferior due to its high fabrication temperature and chemical resistance is also inferior because this resin is amorphous.
On the other hand, in recent years, resin modifiers which improve melt flowability and injection moldability without impairing superior characteristics of a polycarbonate resin, and thermoplastic resin compositions using these modifiers are required because those molded articles can support demands for size increases, thin-walling, forming complex shapes, high performance, and reducing environmental problems and so on.
As a method of improving melt flowability without impairing characteristics (heat resistance, transparency and so on) of a polycarbonate resin, a method of lowering molecular mass of the polycarbonate resin itself, which is a matrix resin, is general. In addition, flowability improvement by introducing polymer-alloys with a particular styrene-type resin (for example, Patent documents 1 and 2) and flowability improvement by introducing polymer-alloys with a particular methacrylate-type resin (for example, Patent document 3) are proposed.
Also, as a further flowability improvement, a method of adding a polyester oligomer (for example, Patent document 4), a method of adding an oligomer of polycarbonate (for example, Patent document 5) or, a method of adding a styrene-type copolymer with a low molecular weight (for example, Patent documents 6 to 8) are proposed.
In addition, lamp covers made up of aromatic polycarbonate resins such as polycarbonate resins produced from 2,2-bis(4-hydroxyphenyl)propane (bisphenol A as a popular name) have been conventionally used for lamp covers such as lenses for headlamps of automobiles and so on, because they are excellent in mechanical characteristics such as transparency, heat resistance and impact resistance.
In recent years, while a demand for large headlamps of automobile has risen, a demand for large, light weight, and thin-walled lamp covers has also risen. The material with excellent melt flowability while maintaining superior characteristics of an aromatic polycarbonate resin, that is, the material being excellent in moldability of injection molding and so on, is needed to make a lamp cover large, light weight, and thin-walling without impairing superior characteristics of lamp covers made up of aromatic polycarbonate resins.
As a method of improving moldability of resins, (1) a method for lowering molecular mass of a resin for obtaining high melt flowability is general.
In addition, in Patent documents 9 and 10, as a lamp cover excellent in heat resistance, (2) a lamp cover comprising an aromatic polycarbonate resin having 9,9-bis(4-oxyphenylene)fluorene structural unit or 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane structural unit is proposed.    Patent document 1: Japanese Examined Patent Application, Second Publication No. Sho 59-42024    Patent document 2: Japanese Unexamined Patent Application, First Publication No. Sho 62-138514    Patent document 3: Japanese Patent Publication No. 2622152 Patent document 4: Japanese Examined Patent Application, Second Publication No. Sho 54-37977    Patent document 5: Japanese Unexamined Patent Application, Second Publication No. Hei 3-24501    Patent document 6: Japanese Examined Patent Application, Second Publication No. Sho 52-784    Patent document 7: Japanese Unexamined Patent Application, Second Publication No. Hei 11-181197    Patent document 8: Japanese Unexamined Patent Application, Second Publication No. 2000-239477    Patent document 1: Japanese Unexamined Patent Application, Second Publication No. Hei 6-65362    Patent document 2: Japanese Unexamined Patent Application, Second Publication No. Hei 7-90073